You cannot "import" linetypes, text and dim styles with Content palette.
As I wrote before, you can save the drawing with all your linetypes, text and dim styles, layers as a template. Be sure to leave this drawing without any visible objects (lines, circles, text, etc).
Than use this custom template for new drawing creation.

If you already have some drawing and want to "import" linetypes, text and dimension styles, etc into it, you can use INSERT command to insert your custom template (exploded). Than everything from the template will be inside your current drawing.

Maxim